Method of cutting steering gears



R. BISHOP l METHOD 0F CUTTING STEERING GEARS June 12, 1.928.

Filed May 21, 1924 2 Sheets-Sheet l June 12, 192s. 1,613,488

R. BISHOP METHOD OF CUTTING STEERING GEARS Filed May 2l, 1924 2 Sheets-Sheet 2 Patented `une 12, 1928.

REGINALD BISHOP, oF noNDon; ENGLAND.

METHOD OF CUTTING STEERING GERS.

Application ined May ai, 1924, serial No. 714,985, and. in Greaemitainfauiy 25, 1923.

This invention has relation to gearing that is particularly, but not exclusively, appli cable in connection with theactuation and control of, the leading or steering road wheels of ii'iechanically propelled road vehicles. t The invention is applicable inrother connections and may be employed in ,or in connection with the actuation andcontrol of the throttle of internal ycombustioneengines and the control of the time of ignition rof the f explosive charges of such engines.` i

`The invent'on has relation to gearing o the kind comprising a camr constituted of a Worm `fixed on an operating shaft and enf` gaged by aroller mounted onan arm so as tol be substantiallyA at right angles thereto, the arm, in turn, lbeing mounted so as to be movable angularlyand in a plane that is substantially parallel to the longitudinal axis of the worm,the roller through its mounting being co-operant with other inein-` bers of the gearing,y

@In gearing of the kind referred to, in ac-` coi-dance with this invention, a cam of helical form and of constant diameter is engaged by a pin or roller mounted on an arm that is angularly movable in a plane parallel tothe longitudinallaxis ofthe cam, said arm being mounted on a rocker shaft andthe axes ofthe arm and of the pin or roller being at rightfangles and the cani beingof a shape that is formed by subjecting the cam blank to the action of a fixed to'ol'whose operative `edge or face atthe same angley asthe face of the roller, the cam blank being rotated and at the same time subject to a compound traversing' movement comprising two components, one of which is in the same direction as the longitudinall axis of the cam blank, and the othersuch that any point of or on the blank moves in thearc of acir# cle Wlioseradius is equal to the length4 of the i'oller `carrying arm between rthe centre ofthe rocker shaft and the axis ofvrotation of the roller,`the two component movementsl occurrii'ig' simultaneously and being effected withoutany change in direction of the longitudinal axis ofthe cam blank. j

Furtherin gearing of the kind referred to, in accordance with this finvention,` the cam may be produced by rotating the cam blank and at the sametime moving the tool in relation thereto, the movement of the tool beinga compound one and comprising two components of which one is in thesame directionas the longitudinal axis of the cam blank andthe other such thatfany point of. i 0r on ,the `tool movesin the arcof a lcircle whose, radiusis equal to the length of the roller lcarrying arm between the centre of the rocker shaft and the axis of rotation of the roller, the'two component movements oct curring `simultaneously and being effected without any .change in direction of t-he axis of the tool.

The tool maybe either a njiilling cutter or a grinding wheel. Y t

`In oi'der tha-tthe invention maybe clearly and readily understood, reference willnow be made to they accompanying drawings, on which:-'i d Fig'. l `is a longitudinal sectional view of the steering gear of a mechanically propelled road vehicle with a cam of the shape herein defined; f t e e c Fig. 2f a section on theline A-B, Fig. l; andh', ,i t i, i 3 a'flongitudinal section through the canrp y e Fig. t is a side elevation ofa machine for cutting a cam in accordance with this invention and of the form described and illustrated in the specific-ation of co-pending` apy' Fig. 6 is a cross section on the line y of Fig. 5. V

Referring to v1,2 and l is the steeringpillarand 2 is the shaft that extends therethrough and carries at its upper endthe steering wheel and at its lower end the cam?) which is of the shape herein de-J. fined and cut in apparatus as described lin the specification of application for Let-tersy Patent Serial No. 714,986, filed May 21, 1924 by the `applicant herein. tis a roller that .engagesthie'cani 3, its :face being inclined to the same angle as the operative faces of the cam. -The rollert is mounted ona pin 5 which is itself mounted on and at right-an-` gles to the longitudinal axis of an arm 6.

7 that is rotatably mounted inbearings 8 in thecasing AS) thatcontains the cam 3., The other end ofthe shaft 7, which hasa rookf ing motion,` is connected with the leading or steering road Wheels of ythe, vehicle in any e `convenient manner.

rThe arinG is mounted on one end of a shaft for a carrier14.

the longitudinal axis of the cam i3., comes on the side of a plane remote from the rocker shaft 7, said plane passing through the lon-i its 'longer sides and extending thefull length thereof. A plate 13 is secured on the upper face of each of the ribs 12, each plate being wider than its supporting rib 12 Abut of the same,`or practically the same, length, and so mounted that it extends overa portionI of tlie'hcd 11. -The plates 13 in conjunction with the 'hed 11 and ribs 12 constitute lguides The Vcarri-er 14 consists of a flat metal plate of such width thatwliatever position it may 'assume'during its traversing movement it is always in engagement with'the guides 1Q, The lengthof the carrier 14 is also such that itis alwayssnpported-over the whole ofits areahy the hed 11. 15, 1G are headstocks xedly mounted on "thebarrier 14. The back centre of the headstock 15 is adjustable as to position 'and is *moved'by 'gearing contained within the headstock and lactuated by a milled or knurled head 15. 17`is ashaft that extends through the headstock 1G and carries on its end adjacent the headstock 15 work carrymg means. such a chuck. The other end of the shaft 17 is connected with gearing such `that 'rotary motion is imparted thereto and through it to the work and also the traversing movement to the carrier. AThe shaft 1,7 issnpported in a second hearing 18 fixedlyinountedon the carrier'lfl. `1`97 '19 are circular holes which 'are formed in the upper face of the hed llzvthe holes 19, 19 are disposed inline and each is disposed towards one end of the hed 11. 20. Q() are circular holes `formed in the lower face of the carrier 14': the lioles 20, t2() are disposed in line and spaced the same 'distance apart as the holes 19. 19. hut with their centres displaced so that they overlap partially theholes 19. 19.

Mounted in each pair of holes 19, 2O is a member of a pair of parallel links each constituted of two circular discs 21, 9.2. The two discs constituting alink are riveted or otherwise `secured together 'or are integral, the"discs .being so connected o'r fashioned that their-"centres `are displaced. the displace-` I1'ientliei`r1rT the same as that of the centres of theholes 19. Q0. j The discs 21 are placed withinfthe holes 19 and ithe discs 22 within the holes 20. and Vare rotatable in relation tlierto." `llVh'en the carrier 14 is traversed as hereafter explained, the discs 2l, 22 move in a rotary sense in the holes 19, 20, respectively.

23 is a framework or structure mounted on the one end of the bed 11 and carrying the gearing by which the shaft 17 is rotated and the carrier 14 is traversed. 24C is a driving pinion, the shaft of which is mounted in a bearing 25 on the framework 23 and is driven either directly or indirectly from a prime m'over there being suitable gearing between thel shaft and prime mover to produce either forward or'reverse motion. The pinion 24: meshes with a spur wheel 2G mounted on a shaft 27 thatis carried in hearings in the framework E23. The shaft 27 also carries a worm 28 which meshes with a worm wheel :29. The worm wheel 29 'drives the shaft 17 hat is not mounted directly thereon. The worm wheel 29 comprises a rim on the periphery of which the teeth are cut anda flange 30 hy which it isbolted *to a flange 31u11 one end of a sleeve 32 that :is mounted Aon the shaft 1.7'andwith 'which it has a feather aud'sljot connection. yOn the other endof the sleeve 321m annular disc 33 is screwed. The flange 31 and the annular disc 33 ycome on opposite sides of a portieri of the framework 23 and constitute stops to prevent or limit endwisc movement of the sleeve 32 in relation to the shaft 17: they also constitute guides. The shaft 17 and sleeve 32 are in driving connection hut the ahle by other members of different pitch,y

and similarly the links 21. 9.2 may he replaceahlehy other links whose centres are displaced to a kdifferent extent.

The arrangement of the parts described is such that when the pinion 24 is driven, its motion is transmitted through the Spur wheel 26, worm 9.8and worm wheel Q9 to the shaft 17 which is rotated; as the shaft 17 is rotated it is also caused to move endwise owing to the engagement of the sleeve 34 with thenut 35. The rotary motion of the shaft 17' is transmitted to the work mounted in the headstocks 15. 16` and its endwise movement to the carrier 14 which is caused to move similarly and owing to its linkage with the bed 11 to travel in `a path such that Sii any point `on the carriermoves in the are of l worm wheel 29 is provided with the guides 3l, 33. The worm 28 is also made of such length that it remains in mesh with the worm wheel 29. The gearing described is so designed that the tool will complete its cut while the carrier 14 is moving from one end position to the other. f i

The tool is so mounted in relation to the work when the bed l1 is in a. horizontal positionthat it will commence and complete its' cut on one and the same side of a vertical plane vpassing through the longitudinal axis of the work and during its operation the work will be moved so that the` said plane is brought under the tool twice, and

between such times the tool operates on the other side of the plane to that at which it commences and completes its cut. y

The cam 3 produced on the apparatus described above has a -pitch which varies from one end thereof to the other, and as shown on the accompanying drawings, but it may be desirable in some cases to employ a cam having a constant pitch and in such case the cam is cut in manner described, the nut being mounted so as to be capable of'controlled and limited rotational and rectilineal move-v ment in both directions, its rotational movement in eachdirection vbeing such that its rectiline'al movement is equal to the length of Aa line perpendicular 4to the chord joining the ends of the arc of movement of the work holder, said line being situated midway of the ends of the chord and extending to the 'said arc of movement.

It will be understood that with the arrangement illustrated, the cam blank is moved in the direction of its axis at a constant rate, but that in the modification described, owing to the compound movement of the nut, the cam blank is moved inthe di-u rection of its axis at a varying rate.

Gearing of the kind referred to and in ac-` cordance with this invention has several advantages in practical and every day use, for example, the mounting ot the roller directly on the arm and carrying the arm beyond thel rentre line of the cam permits a large range of movement and at tlre same time Lhas greater length when considered as a lever in comparison ywith the usual worm and sector or worm and nut mechanism of the same size; this has the eil'ect of reducing the working pressures andenabling plain bearings to be used; the mechanism is compact, easily assembled and contained in a casing of small dimensions. The cam 3 is of a shape" that can be cut cheaply and expeditiously; the roller 4 having a line rolling contact with the cam, friction and wear are reduced.

Whatl claim is l. A method of cutting agear member which consists in rotating a blank in relation to a tool andlsimultaneously producing a relative traversing movement between the blank and the tool, said traversing move- `ment being identicalwith that of the one and movable vmemberof a pair of parallel pair of parallel rulers. y I

3. A method of cutting a gear member which consists in rotating a blank in relation to a tool whose operative edge is at the same angle to the blank as the operative edge; oi a second gear member which will cooperate with the ygear member being cut and simultaneously producing a relative traversing movement between the blank and the tool, said traversing movement being identical with that ot' the one and movablemembei' or' a pair of parallel rulers.

Il. A method of cutting a gear member which consists in rotating a blank in relation to a fixed tool whose operative edge is `at the ysame angle to the blank as the operative edge olI a second gear member which will cooperate with the gear member being cut and simultaneously imparting `to the blank a traversing movement in relation to the tool which is identical with that of the one and movable membergof a pair of parallel rulers. A 5. A method of cutting a gear member which consists in rotating a blank in relation to a tool and simultaneously producing a relative traversing movement between the blank and the tool at a varying rate said traversing movement Vbeing identical with that of the one and movable member of a pair of parallel rulers.

`G. A method of cutting a gear member which consists in rotating a blankin relation to a iixed tool and simultaneously imparting to the blank a traversing movement in relation tothe tool at a varying rate which is iineiiviiiin BISHOP,

identical 4with that of the one and movable v 

